This invention relates to a latch device and more particularly one which is self-latching. The latch device is primarily intended for the latching of a sliding window sash in the closed position in a window frame.
Currently there are a number of self-latching window sash latches available on the market. In most cases the latch operates after the window has been physically closed. Thus when the latch has reached the same level as the strike it latches the window in the closed position. To open the window an operating member e.g. a pull lever is operated and is held in the “open” position until such time as the latch has been lifted or slid past the strike. The operating member is then released.
One problem with this type of latch device arises when disengaging the latch from the strike. As described above the action of opening the window involves holding the operating member and at the same time physically lifting or moving the window. Not only is this action awkward to perform but also it can be very difficult to perform on large windows, windows without finger grips, windows with more than one latch and windows which have limited/restricted access.
A second problem is related to security and safety. With known latches there is no indication once the window sash has been moved to its fully closed position as to whether the latch has in fact successfully engaged with the strike. Thus a window thought to be latched may, in fact, be unlatched which can give rise to potential safety and security risks.